President George W. Bush said he has never ordered the torture of Iraqi or al-Qaeda prisoners as the White House released secret documents showing the use of dogs to induce fear was approved at Guantanamo Bay.

The White House release of a thick file of newly declassified papers tried to demonstrate that Bush and his top aides, in setting policy on interrogation methods, insisted that detainees at Guantanamo Bay, Cuba, be treated humanely.

Two Australians, Adelaide-born David Hicks and Sydney man Mamdouh Habib, are being held at Guantanamo.

"Let me make very clear the position of my Government and our country: We do not condone torture. I have never ordered torture. I will never order torture. The values of this country are such that torture is not a part of our soul and our being," Bush told reporters at the White House.

But Democratic Senator Patrick Leahy of Vermont accused the White House of releasing a "self-serving selection" of documents. "The stonewalling in the prison abuse scandal has been building to a crisis point," he said.

The documents showed the Secretary of Defence, Donald Rumsfeld, in December 2002 approved harsh interrogation techniques for Taliban and al-Qaeda prisoners at the US Naval Base in Guantanamo, only to rescind many of those weeks later and approve less aggressive techniques in April of 2003.

Treatment of the Guantanamo detainees, including interrogation methods, has come under scrutiny following a scandal over abuse and sexual humiliation of Iraqi prisoners by US forces at Abu Ghraib prison near Baghdad.

Rumsfeld originally approved aggressive interrogation tactics at Guantanamo Bay after military leaders there complained in a memo that "current guidelines for interrogation procedures at GTMO limit the ability of interrogators to counter advanced resistance".

The Guantanamo Bay leaders requested permission to use a wet towel and dripping water to induce "the misperception of suffocation" and the use of "mild, non-injurious physical contact such as grabbing, poking in the chest with the finger, and light pushing".

In response, in December 2002 Rumsfeld approved tactics such as forcing a detainee to stand up for up four hours, forced isolation for up to 30 days, deprivation of light, use of 20-hour interrogations, removal of clothing, forced shaving of facial hair, "inducing stress by use of detainee's fears (e.g., dogs)," and use of mild physical contact that did not cause injury.

A Pentagon legal brief recommending the use of the tactics argued that the proposed techniques were likely to pass constitutional muster as long as they were applied "in a good faith effort and not maliciously or sadistically for the very purpose of causing harm".

"The federal torture statute will not be violated as long as any of the proposed strategies are not specifically intended to cause severe physical pain or suffering or prolonged mental harm," the legal brief said.

White House legal counsel, Alberto Gonzales, played down some of the documents produced by lawyers as "abstract legal theories" that "do not reflect the policies of the administration ultimately adopted".

The methods actually used, according to a memo, fell somewhat short of what Rumsfeld approved, such as yelling, 20-hour interrogations and deprivation of light and forced shaving.

Rumsfeld abruptly rescinded most of the aggressive tactics in a January 15, 2003, order and said if any of them were believed needed a request should be forwarded to him for a decision with a "thorough justification" and a "detailed plan for the use of such techniques".

Then in April 2003, Rumsfeld outlined a new list of milder interrogation techniques that permitted significantly increasing the fear level in a detainee, "sleep adjustment," "changing the diet of a detainee" with no intended deprivation of food or water, and isolation of detainees.

White House officials insisted the broad policy was that prisoners should be treated humanely, but included in the documents was an active discussion of how far interrogations could go without being called torture.

"We're going to be aggressive in our interrogations. There's no question about that," Gonzales said. He insisted that the United States would not engage in torture and said the administration uses the definition of torture provided by Congress as "a specific intent to inflict severe physical or mental harm or suffering".

The documents outlined previous and current techniques for nearly 600 al-Qaeda and Taliban prisoners now at Guantanamo Bay, most taken in Afghanistan.